


Substitution

by AfflictedwithAlliteration



Series: Dark Chocolate [10]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap (Undertale), Angst, Hurt No Comfort, Non-Linear Narrative, POV Second Person, Reader-Insert, Soulmates
Language: English
Status: Completed
Published: 2020-02-25
Updated: 2020-02-25
Packaged: 2021-02-27 22:00:01
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,118
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22852873
Author URL: https://archiveofourown.org/users/AfflictedwithAlliteration/pseuds/AfflictedwithAlliteration
Summary: You were always just a stand in.
Relationships: Sans (Undertale)/Reader
Series: Dark Chocolate [10]
Series URL: https://archiveofourown.org/series/848361
Comments: 16
Kudos: 77





	Substitution

You knew it. 

The moment you met him and there was nothing. Soulmates always had the look, the feel, and so…you just _fucking knew_ , knew it was going to hurt. But you couldn’t stop yourself, like watching some car crash play out in front of you.

* * *

“HUMAN! YOU LOOK ADORABLE, JUST LIKE I THOUGHT.”

You flush at the compliment, soaking it up like a flower in the sun. His battle body armor is just big enough to be too big for you, but it made the perfect Halloween costume. And him in your floral pattern outfit was ridiculous but swapped costumes had seemed—

“Perfect! You look adorable too!”

You press a quick kiss to his cheek.

* * *

Everything feels too tight, your ears ringing, and you couldn’t even say where you are, but you remember his face. The hearts in his eyes, the way he takes several moments to even realize you’ve both stopped talking. The way his gaze darts back to them over and over and over. 

It’s your nightmare for weeks.

* * *

You scoff. “Oh c’mon. No one believes in soulmates.”

“I’m serious!” You friend chides, sounding wistful. “Only monsters can but it’s real! I went to a wedding with my cousin the other day. She said it was like…like she’d found a part of herself.”

But you can’t help that it sits in the back of your mind as the monsters continue to breech the surface.

* * *

“It’s tradition.” Your voice is teasing, maybe a bit breathless and the night is way too chilly and wow does the sky look way more interesting when you’re avoiding eye contact. In fact, maybe you can see the big dipper right over the tree line while Sans just stares at you. His gaze is like pop rocks on your skin, sharp and satisfying until he speaks slowly but it doesn’t hide the amusement under it. 

“I AM…AWARE OF HOW NEW YEARS WORKS.”

“Really?” Are you always this high-pitched? Gods, it’s too hot now, wasn’t there a breeze before? You shift awkwardly then try again. “Y-yeah. Of course, I just meant…ya know…if someone tries to kiss you don’t be surprised. Or something.”

You cough into the silence that follows, the countdown being just loud enough to drown out your heart pounding as it starts.

“…YES. WELL, THEN LET’S GO IN BEFORE WE MISS ALL THE KISSING FESTIVITIES.”

Or before you said something else stupid. 

“BUT FIRST.”

It’s easy to forget he’s more than an inch or two taller until he’s using your upturned face as easy access to your lips. 

“What—”

“I WANT TO FINISH AND—” his cuts off as the fireworks start to go off, people shrieking drowning out the white noise in your mind as he presses another kiss to your lips, this one lingering. “START ALL THE YEARS WITH YOU.”

* * *

There’s silence and you’re the most sober you’ve ever been. 

“It’s fine I’m not…upset. I kinda figured, ya know? Soulmates usually have that click, unless you’re not telling me something?”

A poor attempt at a joke after he’d stuttered out the no, face going paler—which you hadn’t thought possible until now—eye lights vanishing until he’s rushing you. His hug is fierce and a little too tight. Always the strongest hugs when he was at a loss for words but then his voice, wobbly enough that you are happy you can’t see his expression, finally breaks the silence. 

“I WOULD NEVER DO THAT TO YOU.”

The ‘if I could help it’, lingers heavily after.

* * *

You're laughing so hard you're crying while Sans sputters out some sort of curse but it's mostly hissing before he points a finger at you defiantly.

"RE-MATCH!"

"You're on!"

"I'LL WIN FOR SURE THIS TIME!"

"Oh yea-" You're cut off by him plopping himself in you lap. It blocks your view entirely and you burst out laughing, tears of mirth stinging your eyes and smearing your makeup. "Cheater!"

"THERE IS NO RULE AGAINST SITTING IN MY DATEMATES LAP!"

You win anyway because you can't resist pressing a kiss to the back of his neck and he drives straight into the wall for a good five minutes.

* * *

He was never yours. 

He isn’t even yours now.

_You’d known better._

The pressure behind your eyes in unbearable, and your mouth opens wetly when you speak, already cracked. He’s shaking his head like he’s going to deny it, but you speak first.

“You love them.” You don’t bother to stop yourself from crying, speaking through the salt. “So go.”

“DATEMA—“

“ _Please don’t._ ” 

The desperation in your voice stops his words instantly. You can’t do it. You can’t have him lie to you forever. Lie to himself. The little bit left of your heart, maybe of your soul, can’t do it anymore. Your chest physically hurts and you feel yourself growing tenser because he’s going to make you make the first move again. Something like a laugh leaks out.

“I’m done, Sans. We’re done.” It’s so much easier to say them than you’d thought. 

* * *

"I LOVE YOU." 

It's abrupt in the dim light and you jerk a bit before facing him in surprise. His eyes are tiny hearts, skull a faint blue, and he isn't reading the book anymore. You don't even know when he stopped, but he had clearly been watching you for more than a minute. Hotly, you feel yourself flush but you don't look away as you put your phone down and press your forehead to his, reveling in the closeness.

"I love you, too."

* * *

You stare at the wedding invitation blankly. Six months ago he'd been yours. Six months ago you thought it'd be your name by his and you don't hesitate to rip the card in two. Maybe he thought you were fine already. Maybe he thought you were a bigger person. Maybe he wanted his best friend there but you toss it in the trash as the tears start again, like they'll never stop.

It was no different than anything else. Than anyone else. It’s fine. You weren't dead. Just dumped. You glare at the ceiling but it's more of a plead to make it unreal because the tiniest part of you had hoped he'd come back. That all those moments hadn't been you standing in till his "true love soulmate" came into the picture but...

You think about everything you'd already known. Yeah. That was your misstep. You'd known all along that...

* * *

"HELLO, I'M SANS!" 

He introduces himself like you would in elementary school, complete with a shy handshake and you grin. He's sweet.

"I'm-"

Your own introduction falls short as someone calls him, another skeleton, and he slips away.

* * *

He was never yours anyway.


End file.
